In modern marine seismic streamer systems, a vessel tows a long cable supporting a large number of sensors. Recent developments in such systems have simultaneously focused on making such cables light, durable, and easy to manufacture and maintain, as well as sensitive to the acoustic signals of interest while remaining relatively immune to noise. These developments lead to improvements disclosed in U.S. Pat. No. 6,128,251, assigned to the same assignee as the present invention.
In U.S. Pat. No. 6,128,251, there was disclosed a structure of a solid marine seismic cable which included an interior cable, a surrounding woven strength member, an overlying foam floatation layer, and an enclosing jacket. One or more elongate channels were formed in the overlying floatation layer, and one or more piezoelectric elements were mounted in the channel(s). The elongate form of the channel enlarges the acoustic aperture for improved reception of seismic signals.
Further testing of the structure disclosed in that patent proved the efficacy of the structure disclosed therein, and has resulted in certain improvements and refinements, which are the focus of the present application. Many drawbacks then known in the art were solved by the structure disclosed in U.S. Pat. No. 6,853,604, incorporated herein by reference. However, the improvements and refinements have continued.
More particularly, we have found that previous solid marine seismic cables suffer extreme stresses at the ends of the hydrophone body when the cables are reeled onto a cable reel aboard a vessel. This is due in large part to the fact that the body is rigid and the cable forms a sharp bend at each end of the body when it is wrapped around the reel. These extreme stresses have been found to result in premature failure of the cables. The present invention is directed to solving these and other drawbacks in the art.